How severe is CVE-2018-4850?

CVE-2018-4850 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-4850 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-4850?

CVE-2018-4850 primarily affects Siemens Simatic S7-400 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-4850?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-4850 published?

CVE-2018-4850 was published on 2018-05-16 and last updated on 2026-06-17.

CVE-2018-4850

CVE-2018-4850 is a high-severity vulnerability in Siemens Simatic S7-400 Firmware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 3% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Siemens Simatic S7-400 Firmware
Published: 2018-05-16
Last modified: 2026-06-17

Description

A vulnerability has been identified in SIMATIC S7-400 (incl. F) CPU hardware version 4.0 and below (All versions), SIMATIC S7-400 (incl. F) CPU hardware version 5.0 (All firmware versions < V5.2), SIMATIC S7-400H CPU hardware version 4.5 and below (All versions). The affected CPUs improperly validate S7 communication packets which could cause a Denial-of-Service condition of the CPU. The CPU will remain in DEFECT mode until manual restart.

Frequently asked questions

What is CVE-2018-4850?: A vulnerability has been identified in SIMATIC S7-400 (incl. F) CPU hardware version 4.0 and below (All versions), SIMATIC S7-400 (incl. F) CPU hardware version 5.0 (All firmware versions < V5.2), SIMATIC S7-400H CPU hardware version 4.5 and below (All versions). The affected CPUs improperly validate S7 communication packets which could cause a Denial-of-Service condition of the CPU. The CPU will remain in DEFECT mode until manual restart.
How severe is CVE-2018-4850?: CVE-2018-4850 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-4850 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-4850?: CVE-2018-4850 primarily affects Siemens Simatic S7-400 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-4850?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-4850 published?: CVE-2018-4850 was published on 2018-05-16 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:siemens:simatic_s7-400_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_s7-400h_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Simatic S7-400 Firmware

CVE-2018-16557 — High (CVSS 8.2): A vulnerability has been identified in SIMATIC S7-400 CPU 412-1 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 DP V7…
CVE-2018-16556 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC S7-400 CPU 412-1 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 DP V7…
CVE-2017-2681 — Medium (CVSS 6.5): Specially crafted PROFINET DCP packets sent on a local Ethernet segment (Layer 2) to an affected product could cause a…
CVE-2017-2680 — Medium (CVSS 6.5): Specially crafted PROFINET DCP broadcast packets could cause a denial of service condition of affected products on a…

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